1. Field of the Invention
The present invention relates generally to brakes in vehicles and, more specifically, to an apparatus and method for measuring brake bias in a brake system on a vehicle.
2. Description of the Related Art
Vehicle racing, such as automotive cart track racing, is a specialized and competitive sport involving a vehicle designed specifically for that purpose. A race vehicle takes advantage of available vehicle system technologies that enhance the speed and handling of the vehicle. A brake system on the race vehicle is optimized to maximize the braking force necessary to slow the vehicle down in a minimal period of time, while still maintaining control of the vehicle. For example, in threshold braking, the driver applies the brakes hard at the last opportunity, such as going into a corner, and releases the brakes quickly to regain speed, such as coming out of a corner.
The performance of the brake system is optimized using a ratio referred to in the art as brake bias. Brake bias is a ratio of the braking force applied to one or more wheels relative to a total braking force. A race vehicle typically utilizes a brake on each wheel. The braking force may be biased towards the front brakes, the rear brakes, the left-side brakes or right-sight brakes, depending on the desired braking and handling characteristics for the race vehicle. In a racing situation, the brakes are typically biased towards the front brakes, since a braking force biased towards the rear brakes may increase the possibility of the rear brakes locking up, causing the vehicle to spin under certain operating conditions.
In the past, the brake bias was statically determined by measuring brake-line pressure in a front brake line and a rear brake line and calculating a brake bias ratio. To measure the pressure within the brake line, the brake line is unsealed, a pressure transducer is placed within the brake line, and the brake line is purged. A braking force is applied to the brake pedal, generating a pressure within the brake line. When the pressure in the front brake line reaches a predetermined pressure, such as 1000 psi, the rear brake line pressure is measured. The brake bias is calculated as a ratio of the brake line pressure for one brake relative to a total brake line pressure, using the pressure reading displayed on the pressure transducer. The pressure in the brake lines is adjusted to the desired ratio, such as with a proportioning mechanism, as is known in the art. The pressure transducers are removed from the brake lines, the brake lines are resealed, and purged of air.
While this method of measuring brake bias works, it is time consuming and may result in a variance in the brake bias ratio after sealing and purging the brake lines. Thus, there is a need in the art for an apparatus and method of accurately measuring brake bias in a timely manner.
Accordingly, the present invention is an apparatus and method for measuring brake bias in a brake system on a vehicle. The apparatus includes a brake bias measuring pad, such that the brake bias measuring pad is operatively positioned within a brake caliper in the brake system. The apparatus also includes a load measuring mechanism disposed within the brake bias measuring pad, such that the load measuring mechanism measures a load applied by a brake caliper piston on the brake bias measuring pad. The method includes the steps of measuring a load applied by a brake caliper piston on a brake bias measuring pad operatively positioned within a brake caliper in a brake assembly of the brake system. The method also includes the steps of determining a brake caliper pressure based on the load applied by a brake caliper piston on the brake bias measuring pad and determining a load in the brake caliper based on the caliper pressure. The method further includes the steps of determining a brake bias for a brake assembly as a ratio of the brake caliper load for the brake assembly versus a total of the brake caliper loads for each brake assembly in the brake system and adjusting the brake pressure in the brake system based on the brake bias.
One advantage of the present invention is that an apparatus and method for measuring a brake bias in a brake system on a vehicle is provided that accurately determines a braking force on a wheel. Another advantage of the present invention is that an apparatus and method for measuring a brake bias is provided that quickly determines a brake bias ratio. Still another advantage of the present invention is that an apparatus and method for measuring a brake bias is provided that determines the braking force on a wheel that is less intrusive.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.